Program-selecting circuits



May 1, 1928.

.I. F. TOOMEY PRO GRAN SELECTING CIRCUITS [)V VENTOR J1? T001229 Filed Dec. 10. 1923 m r W:

A TTORNE Y Patented May 1,1928. v "UNITED STATES PATENT OFFICE.

JOHN I. TOOMEY, OF NEW YORK, N. Y., ASSIGNOB TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A COBPOB-ATION OF NEW YORK.

PROGRAM-SELECTING CIBOUITB.

. Application filed December 10, 1928. Serial No. 679,734.

This invention relates to transmission systems for sendin programs over wires and more particular y to arrangements for the selection of programs for such systems.

Where wire lines, such as ordinary telephone lines, for example, are used for the transmission of entertainment programs, such as news, lectures, concerts and the like,

it is desirable that some arrangement be 1 provided whereby tlie subscriber may automatically select the particular program which he desires to hear. In accordance with the present invention it is proposed to accomplish this result by providing a selective switching arrangement at the central oifice for connecting the terminals of the subscribers line to the terminals of any one of a number of trunks each leading to a difierent program. Controlling devices are also provided at the central office whereby the operator, upon being informed by a subscriber as to the program desired, may control the switching arrangement to select the program.

By the use of a selective switching arrangements -for selecting programs it becomes immaterial whether the program be transmitted at voice frequencies or carrier frequencies and -it also becomes immaterial whether several programs be transmitted at the same frequency or whether different carrier frequencies are used for different programs. The switching arrangement emplo ed may be of any well known type, but

as erein disclosed it comprisesa' relay selecting device for making the desired connections.

The invention will now be more fully understood from the following description 40 when read in connection with the accompanying-drawing, the figure of which illustrates a preferred embodiment of the invention.

Referring to the drawing, L designates an 46 ordinary telephone transmission line terminating in the usual subscribers set S at one end and terminating at the central oflice in the switching jack J. Normally, the telephone line is connected over the contacts of 50 the cut- 01f relay CO toa transformer"20 whereby the' line is associated with conductors 11 leading to a relay switching arp rangement for connecting the line with the desired program. The line relay LR has its 66 windings connected on either side of a conwhich is as follows:

denser 21, which is interposed between the two halves of the secondary winding of the trmsformer 20. The cut-off relay CO is so arranged that when it is operated the line L is disconnected from the transformer 20 and hence from the line relay LR, the'line being then connected directly ring terminals of the jack J.

program transmission during such time as it is not being used for ordinary telephone purposes, a program receiver, such as the loud speaker LS at the subscribers station is provided, said receiving device bein bridged across the line through the bac contact of the switchhook 10 and through the contact of a high resistance relay 23. The relay 23, which controls a circuit of the loud speaker LS, is so arranged that it will be operated to connect the loud speaker upon the momentary actuation of the non-locking key K to close its contact 33. On the other hand, the relay 23 is so arranged that it will be released to disconnect the loud speaker upon takin the receiver from the switchhook to make the call, or upon the operator inserting the plug into one of the multiple Jacks to call the subscriber. It may also be to the tip and In order that the line may be used for released by the subscriber when he no longer desires to hear a program by means of a contact 31, controlled by the key K.

At the central oilice,*a plurality of trunk? leading to different program s,-indicated on the drawing as A, B and" C, "are provided. In order to connect any particular trunk to the line over the conductors 11 a relay selective arrangement is provided comprising relays 40 and 41, controlled by selective-reing to program A is'connected to the line L over the contacts of the relays 40 and 41. Upon the operation of relay 40, however, program A will be disconnected from the line and program 0 will be connected instead. If relay 41 is actuated, program B is connected to the line exclusively. In order to control these relays a jack J is lays 42 and 43. Normally, the trunk leadarranged at the central oflice and the operator is provided with a controlling circuit comprising keys A, B and C, which may brla assleciated with the jack J through the ug 4 Further details of the ap a'ratus will be clear from the descri tiono the o ration, en the line is not in use for telephonic purposes and the sub- .the substation set in the usual manner in making a telephone call, thereby energizing the line relay LR to signal the operator. The operator then plugs into the jack J in the usual manner, thereby energizing the cut-off relay CO and connecting the line L to the tip and ring terminals of the jack J. Upon ascertaining that the subscriber wants program B, the operator withdraws the plug of the cord circuit from the jack J, thereby releasing the cut-off relay CO and again connecting the line L through the transformer 20 to the conductors 11. The operator at the same time'inserts the plug P of the control circuit in the jack J and momentarily actuates the key B. This closes a circuit from battery, over the middle and upper contacts of key B, over the sleeve'conductors of the plug P and jack J and through the winding of the relay 50 to ground. Relay 50, upon being momentarily energized by the momentary operation of the key B, opens the locking circuit of relay 42 or relay 43, in case either energization of relay 40 'or 41 in case either of these relayshas been actuated, thereby restoring the normal connection-of the conductors 11 to the program A.

The momentary depression of key B also closes a circuit from battery, over the midv dleand lower contacts of said: key, over the releases u ringconductors of the plug P". and jack J and through the upper winding of the relay 43 to ground. Relay 43 is energized and at its lower contact completes a circuit through its locking winding and over the back contact of rela to ground, thiscircuit being complete as soon as therelay 50 n the release of the key B. The relay 43 1s slightly'slower in releasing its armature than the relay 50 and consequently upp'er winding is deenergized. At its upper :contact relay 43 closes a circuit through relay 41 in series with relay 52. Relay 41 .dis-

connects conductors 11 from program A and connects said conductors directly to program B. The circuit of the resistance 53, bridged across the trunk leading to program B, is at .the same time opened. Belay 52,.on the other hand bridges a-rcsistance 54 across the trunk leading to program 'A so that the.

' contact to thetrunk'leading to program trunk will have the proper impedance.

The 0 rator ofcourse, withdraws the plug P" fromthe. jack J "as soon as the seection is made, and the connection of the line L to the program B will remain in the condition just-described, regardless of what may take place in connection with the line L, unless the subscriber calls up the operator in the manner already described and orders up a new connection. If the subscriber, for example, should order the program C connected to his line the operator will insert the plug P intov the jack J" as before and operate the key C. This closes a circuit from battery over the'middle and upper contacts of said key and over the sleeve conductors of the plugs P" and jack J,

through the winding of the relay 50 to ground. Relay 50 is momentarily energized as before and opens a locking circuit of the relay 43 so that said relay is released, thereby opening the circuit of relays 41 and 52 and restoring said relays to normal. The

conductors 11 are now connected to the trunk leading to program A and the resistance 54 is no longer bridged across said trunk, while the resistance 53 is again bridged across the trunk leading to program B. p

The actuation of the key C at the same time closes a circuit from batter over its middle and lower contacts, over the tip conductors of plug P and jack J through theupper winding of" relay 42 to ground. Relay 42 is energized and locked up through its lower winding in series with the backcontact of relay 50 as soon as the relay 50 is decnergized. The relay 42 is slightly slower in'releasing its armature than relay- 50, thereby causing the locking circuit of the relay 42 to be closed before the upper winding of said relay is deenergized. At its upper contact relay 42 closes a circuit of relays 40 and 52. Relay 40 connects conductors 11 over the backcontacts of relay 41 and over the front contacts of relay 42 to the trunk leading to program G. The circuit of the resistance 55, which is normally bridged across said trunk, is at the same time opened. Relay 52 at the saine time bridges resistance 54 across the trunk leading to program A so that the impedance of the trunk A will not be changed by discomnecting the line therefrom.

With the circuit in this condition the opllo erator may select program A by actuating the'key A of her controlling circuit when O and connects said conductors over its 21: 7

at'the same time bridging the resistance 55 across the trunkleading to program 0. Re-- lay 52 in the meantime disconnects the brid includmg' the resistance 54 from the truni leading t0 ro A. As soon as th: has requested round.

which. in turnreleases relays 40 and 52. Rela 40 'disc0n-' meets the conductors 11 from I e fproam memes the'central operator to connect his line to a circuit. he relay 23, upon the conversation takes particular program, he immediately hangs up his receiver and momentarily 'actuates the key K to close its contact 33. This completes a ,CilCllit mm batter ,through the right-hand winding of the e relay LR over the lower back. contact of the cut-om rela 00, ring conductor of the line, over the ack contact of the switchhook 10, over contact 31 of the keyK and 'over contact 33 of said key, through the high resistance winding'of relay 23, over the tip conductor of line L, up er back contact of relay CO and through t e right-hand winding ofi'the line relay LR to ground. -The line relay is not energized in series with-the high .resistance of the relay 53 but relay 23 isenergized and completes a locking circuit for its 'windingin parallel with the contact 33 of the key K so that the relay 23 remains energized after the key is restored. At its outer front contact. relay 23 bridges the loud speaker LS across the line so that the subscriber is able to hear the program ordered as soon as the operator has made the connection in the manner previously described.

If, while the circuit is being used for receiving a program a telephone call should come in for the subscriber, the operator inserts the plugof hercord circuit into thejack,

J in the usual manner, thereby energizing the cut-off relay CO. The cut-ofi relay CO shifts its armatures from its back contacts to its front contacts, thereby connecting the lineL to the tip and ring conductors of the 'ack J. This momentarily disconnects the attery supply to the relay 23 through the line relay LR and permits the rela 23 to be deenergized and unlocked before attery is again sup lied to the line L through the cord unlocked,

disconnects the loud speaker from the line. The subscriber, upon being rung, then moves his receiver fromthe switchhook and lace in the usual manner At the end of t e conversation the subscriber hangs up and the operator withdraws the plug from the jack thereby releasing the cut-ofi relay CO. e subscriber may now connect his loud speaker to the line by momentarily actuating the key K to close the contact 33, as already If the subscriber desires to make a call while the line is being used for receiving a program he moves his, receiver from the 'switchhook in the usual manner. The cir- I operator then plugs in operating the cut-ofi relay CO and connecting the line L to the jack J in the usual manner. The conver'sa-. tion proceeds asibefore and at the end'of' the conversation the subscriber hangs up his receiver and the o rator withdraws the plug from the jack :The-subscriber may then again receive the program by momentaril closing the contact 83 or key W 1en the subscriber no longer desires to hear a program he merely actuates the key K to momentarily open the contact 31,.there-- by releasingv and unlocking the/relay 23, which disconnects the loud s er LS from the line. The connection 0 the line to the rogram previously selected remains as beore; however, until such time as'thesubscriber orders a new connection.

' It will be obvious that the general principles herein disclosed may be embodied in many other organizations widely difierent from those illustrated without departineg from the spirit of the invention as defin in the appended claim. I

a What is claimed is:

In a wired program system, a line extending from a central ofice to a pro am subscribers station, a plurality of tru at said central oflice upon which programs may be impressed, resistances to simulate the impedance of said line normally connected to said trunks, and selectively operated relay means for establishing connections ween said line and any one of said trunks and to disconnect the resistance from thetnmk'to which connection is made.

In testimony whereof, I have signed my 100 JOHN F. 'room nr. 

